According to Table 5-21, on page 35 of the f2802x datasheet the typical flash sector erase time is 2 seconds. Im using a f28027, and when I erase sectors A, B, and C using the flash kernel, I measure a total erase time of 2.5 seconds, which is 833ms per sector. I understand that there are lots of variables that go into determining how long a flash erase takes, but being off by 60% of the nominal value seems very odd. Since this part's flash gets damaged when power is lost during an erase, I'm looking into adding voltage monitoring capabilities, and extra capacitance to ensure that whatever operation is taking place during a power loss, there will be enough power to complete the operation, hopefully preventing the bricking of flash.
If actual times can be 60% less than typical times, does that mean they can also be 60% greater than typical times? How can I come up with a reasonable worst case time?